The European Union's competition office on Tuesday opened two antitrust cases against Motorola Mobility for possibly abusing its patents following complaints by two rivals, Microsoft and Apple.

The cases are the latest stage in what has become a full-blown battle over the ownership of essential technologies that help power mobile and gaming devices, a fight that has engulfed Google and virtually all the other major players in the industry.

EU probes Motorola after Microsoft, Apple complaintsEU regulators are investigating whether phone maker Motorola Mobility breached antitrust rules by allegedly over-charging Microsoft and Apple for use of its patents in their products, the European Commission said on Tuesday.

Facebook launches patent counterattack against YahooFacebook fired back on Tuesday in its legal battle with Yahoo by accusing the Web pioneer of infringing 10 of Facebook's patents, according to a court filing.